DEGs detected by RNA-SEQ (excel file).

The study of carrier state phages challenged the canonical lytic-lysogenic binary, and carrier state appears to be ubiquitous and ecologically important. However, the mechanisms of the carrier state are not well elucidated due to the limited phage models. Herein, we reported phage HQ103, similar to Escherichia coli phage P2. In contrast to the temperate P2 phage, the HQ103 phage does not insert its genome into the bacterial chromosome and displays a dual behavior depending on the temperature. At 37°C, HQ103 lyses the host and forms clear plaques due to the truncation of repressor CI and mutation of promoter Pc. In contrast, HQ103 maintains a carrier state lifestyle with Y. pestis at an environmental temperature (21°C). Mechanistically, we found that the host-encoded histone-like nucleoid-structuring protein H-NS, which is highly expressed at 21°C to silence the Cox promoter Pe and inhibits the phage lytic cycle. Subsequently, the HQ103 carrier state Y. pestis could grow and co-exist with the phage in the soil at 21°C for one month. Thus, this study reveals a novel carrier state lifestyle of phage HQ103 due to the H-NS mediated xenogeneic silencing and demonstrates that the carrier state lifestyle could promote long-term phage-host coexist in nature.携带态噬菌体（carrier state phages）的相关研究颠覆了经典的裂解-溶原二元生命周期认知，且携带态现象普遍存在，在生态学层面具有重要意义。然而，由于现有噬菌体模型较为匮乏，携带态的分子机制尚未得到充分阐释。本研究报道了一株与大肠杆菌（Escherichia coli）噬菌体P2同源的噬菌体HQ103。与温和噬菌体P2不同，HQ103并不会将自身基因组整合至细菌染色体中，且其生命周期呈现温度依赖的双重特性：在37℃条件下，由于阻遏蛋白CI发生截短以及Pc启动子产生突变，HQ103会裂解宿主菌并形成透明噬菌斑；与之相反，在21℃的环境温度下，HQ103与鼠疫耶尔森菌（Yersinia pestis）维持携带态生活周期。机制层面的研究发现，宿主编码的组蛋白类拟核结构蛋白H-NS（histone-like nucleoid-structuring protein H-NS）在21℃下高表达，可沉默Cox启动子Pe并抑制噬菌体的裂解周期。后续实验表明，携带HQ103的鼠疫耶尔森菌可在21℃的土壤环境中与噬菌体共存并增殖长达1个月。综上，本研究揭示了由H-NS介导的异源基因沉默所造就的噬菌体HQ103新型携带态生活周期，并证实携带态生活周期可促进噬菌体与宿主在自然环境中长期共存。